Watlow CLS - Manual (Page 118)

110 CLS User’s Guide
Troubleshooting
Checking Computer Supervised Systems
Four elements must work properly in a computer supervised system that
uses an IBM-compatible computer and ANASOFT:
• The CLS.
• The computer and its RS-232 or RS-485 serial interface.
• The RS-232 or RS-485 communications line.
• The computer's software.
For CLS troubleshooting, disconnect the communications line from the
computer before you follow the troubleshooting steps explained in the
previous sections. Troubleshooting for the computer and
communications are explained in the sections below.
Computer Problems
If you are having computer or serial interface problems, check the
following:
• Make sure you are using DOS 5.0 or a later version of DOS.
• Check the communications interface, cables, and connections. Make
sure the serial interface is set according to the manufacturer's
instructions.
• To test an RS-232 interface, buy an RS-232 troubleshooter
from Radio Shack or an equivalent supplier. Attach the trou-
bleshooter between the CLS and the computer. When ANA-
SOFT sends data to the CLS, the troubleshooter's TX LED
should blink. When ANASOFT receives data from the CLS,
the RX LED should blink.
• You can also connect an oscilloscope to the transmit or
receive line to see whether data is being sent or received. If
the serial interface does not function, contact your computer
service representative.
NOTE
Most communications problems are due to incorrect wiring
or incorrectly set communications parameters. Therefore,
check the wiring and communications settings first.
If you have more than one controller, or you are using more than 50 feet
of communications wiring, you must use RS-485 communications.
Otherwise, you can use RS-232 communications. The CLS is
configured for RS-232 communications when it is shipped. If you are
using RS-485 communications, you must set the internal RS232/RS485
selection jumpers to the correct position. (See Chapter 2: Installation for
information about changing jumpers.)